<!DOCTYPE HTML>
<html>

<head>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <title>无标题文档</title>
</head>

<body>

  <ul id="test">
    <li>JavaScript</li>
    <li>HTML</li>
  </ul>

  <script type="text/javascript">
    var otest = document.getElementById("test");
    var newnode = document.createElement("li");
    newnode.innerHTML = "php";
    otest.insertBefore(newnode, document.getElementsByTagName("li")[1])
  </script>

</body>

</html>